Architecture bridging using VST on Windows fails silently

[Simon-L]

I made rather extensive tests on Windows 10 64bit to load 32 bit VSTs using Ildaeil 64bit VST and VST3, it seems to just fail silently.

I tried in hosts: Bitwig Studio 3.2.8, Ardour 7.2 and Carla 2.5.3
I just noticed as I'm writing that Ardour does output some errors (I'm running ardour in mingw terminal) but only when the Ildaeil plugin is deleted in the track:

Will scan plugins now...
Scanning found 21 plugins
[carla] Starting plugin bridge, command is:
C:\Users\xox\Downloads\Ildaeil.vst\carla-bridge-win32.exe "VST2" "C:\Users\xox\Downloads\pecs_1_0_2\pecs.dll" "(none)" 0
dispatcher 12, 0, 0, 00007ffd4b200b80, 0,000000
got error: Timeout while waiting for a response from plugin-bridge
(or the plugin crashed on initialization?)
[carla] CarlaPluginBridgeThread::run() - bridge crashed
Ildaeil-Synth destroying edit window
assertion failure: "fIsActive" in file ../../dpf/distrho/src/DistrhoPluginInternal.hpp, line 924

Can someone try to reproduce? I'm not 100% certain I haven't missed something.
A reasonable test plugin: https://www.fullbucket.de/music/pecs.html using either of the Windows VST versions.

Load Ildaeil VST, "Load from file..." and select pecs.dll, nothing happens.
Click "Load from file..." and select pecs64.dll, it should work. This is the 64bit version so no bridging happens.
http://antonsavov.net/cms/projects/as_sonogx2.html This is the win32-only VST plugin I am actually trying to use.

Note that the same does work in Carla as a plugin (loading the above plugins in Carla as a plugin in one of the hosts mentioned), enabling experimental bridges and Bridged (32bit) in Architecture filter for plugin selection will pick up and load the 32bit plugin, natively on Windows and using wine on Linux.

[Simon-L]

For comparison, here's the output of running Carla.exe in windows cmd where the bridge command is different.
For clarity this is the working case, the plugin does show and work.

[carla] Starting plugin bridge, command is:
C:\Users\xox\Downloads\Carla-2.5.3-win64\Carla\carla-bridge-win32.exe "VST2" "C:/Users/xox/Downloads/Ildaeil-win64-v1.2/Ildaeil.vst\as_sonogx2.dll" "as_sonogx2" 608663602

The name of the plugin and a numerical ID is correctly appended, could this be the cause?

Edit: The line in Carla codebase that outputs this log message is this one.